HP 6177B Operating And Service Manual page 26

p-p
(Model 6177B) or 40mV
p-p
(Model 6l8lB),
8.
Se';: range switches to medium range and
adjust fo:- rated output current
0:
that range.
Observec noise
shotile
be less than 40mV
p-p
(Mociel G177B) or 32mV
p-p
(Mociel SlSlE).
g. S8: range switches to lowest range and
adjus: for
ralec
output curren: of low range.
h. ODse:-ved noise should be less than 50mV
p-p (Model 6177B) or 20mV p-p (Model 6181B).
5-24 LOAD TH.hNSIENT RLCOVER'::.- TIME
Definition: The time "X" for output
current recovery to within "Y" mil-
liamps of the nomina 1 output current
following a liZ" amp stet: change in
load voltage - where:
"Y" is generally of the Seme order
as the load regulation specification.
The nOC1inal output cuaen! is defined
as the de level half way between
the static output current before and
after the imposed load change, and
uz"
is the specified load voltage
change, normally equal to the full
load voltage rating of the supply.
5-25 Transient recovery time may be measured at
any input line voltage combined with any output
voltage and load current within rating.
5-26 Reasonable care must be taken in switching
,the load resistance on and off. A hano-operateci
switch in series with the load is not adequate,
since the resulting one-shot displays are difficult
to observe on most oscilloscopes, and the arc
energy occurring during switching action complete-
ly masks the display with a noise burst. Transis-
tor load switching devices are expensive if reason-
a,.bly rapid load current changes are to be achieved.
5-27 A mercury-wetted relay, as connected in the
logd switching circuit of Figure 5-5 should be
used for loading and unloading the supply. Vlhen
L"1is load switch is connected to a 60Hz ac input,
the mercury-wetted relay will open and close 60
times per second. Adjustment of the 25K control
permits adjustment of the duty cycle of the load
current switching and reduction in jitter of the os-
cilloscope display.
5-28 To check the load transient recovery time<)
proceed as follows:
c. Connect test setup shown in Figure 5-5.
b. Turn VOLTAGE control fully clockwise.
c. Set meter switch to AMPS and range
switch to highest current range.
d. Adjust CURRENT control until front panel
meter indicates exactly the maximum rated output
current.
e. Close line switch on repetitive load
switch setup.
5-6
f.
Adjus: 2SK potentiometer until a stable
display is obtained on oscilloscope. VJaveform
should be within the tolerances shown in Figure
5-6. Output should return to within ::!::lOmV (Model
6177B) or ::!::25mV (Model 61813) of nominal value in
less than 200 mIcroseconds.
POWER SUoPL '(
UNDER TES-:-
115VAC
60Hz
+
o
0
I
aSCILLOSCOP::
hp 140A
9\L9
~
- +
G
RSI
v===~1 I~
i
RES!SIANCE
i
MODEL
NO. r--::-,-,W:::HC;M",S' : -' _ -I
H
i
"SI FlLl
I
61778 2 98
! - - -
-o--,±..i
l
i==6=1=81=B=====I=O==~=3=9=O=
I
I
J
NOTES:
!
l IN:: I
I
I
SWITCH
I : .
THIS DRAWING SHOWS A
I iN3253 SUGGESTED METHOD OF
I
BUilDING A LOAD SWITCH.
HOW:::VER, OTH:::R METHODS
COULD
B::
USED; SUCH AS
A TRANSISTOR SWITCHING
NETWORK. MAX IMUM LOAD
RATINGS
OF
LOAD SWITCH
ARE; 5AMPS 50av,250w
{NOT 2500Wl.
US::: M:::RCURY
RELAY,
CLARE: TYP::: HGO 1002
OR W.E. TYPE 2768
Figure 5-5. Load Transient Recovery Time,
Ie st Setup
1 NOM
-';---.,-<---'-""""-
r+
l %
--'--
INOM-+----~-rc+=:"""-­
I _ -
I l_I"I<>
I I
r-200uSEc-l
UNLOADING TRANS lENT.
L
1 %
LOADING TRANSIENT
Figure 5-6. Loae. Transient Recovery Time,
Vlaveforms
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•